The application conventional 12 volt electronic fuel injectors to automotive electrical systems of much higher voltage such as, for example 42 volts, presents problems to the fuel injector design. Assuming that the typical size of the fuel injector cannot change, and that the fuel injector will most likely be driven by a saturated switch electronic control unit (ECU), major modifications in the coil design of existing injectors will be required. For example, if an existing 14 ohm fuel injector coil consists of 525 turns of #34.5 AWG copper wire, the corresponding coil for a 42 volt operation must be a 126 ohms consisting of 1575 turns of #38.5 AWG copper wire. These calculations follow from the requirement of providing the same number of ampere-turns for an acceptable magnetic force and of maintaining the power dissipation the same in the injector. The use of extremely fine gauge wire is not feasible in the rugged fuel injector environment. For example, by way of comparison, wire size #36 AWG is generally the same thickness as a human hair. Alternate solutions such as adding a voltage dropping resistor in series with the fuel injector coil are feasible, but this solution wastes power and generates substantial heat. Likewise, modifying the standard ECU drivers to regulate injector current is an expensive option, especially when systems of 12 volt and 42 volt capacity may be co-existing in the automotive market for several years.
Accordingly, there is a need to provide a fuel injector having circuit structure to step-down a vehicle electrical system voltage, which is substantially greater than a nominal operating voltage of a fuel injector, to be substantially the nominal operating voltage of the fuel injector.